A retired four-star Marine Corps general, now the U.S. ‘special envoy’ in the war against the terrorist army, on reasons for optimism even as a long fight looms.

Some six months ago, the Islamic State terrorist army poured south from Syria through Iraq’s Tigris and Euphrates valleys, conquering multiple cities including Mosul and the border city of al Qaim. Iraqi army regulars disintegrated, the offensive carved out a rump state controlling somewhere between a quarter and one-third of Iraq’s sovereign territory, and mass executions, repression and videotaped beheadings followed.